ANALYSIS OF BEHAVIOR IN LOWER ORGANISMS 291 



In the experiments of Yerkes, using the two passages to the water, 

 described in Chapter XII, the following are the conditions. The pres- 

 ence of the investigator or the drying of the animal at T, Fig. 139, acts 

 as a stimulus to cause movement away from T. A turn to the right is 

 accompanied, let us say, by the physiological condition A. This is 

 soon followed by contact with the glass plate G, inducing the condition 

 B, which involves inhibition of movement and a turn in another direction. 

 In the course of time the condition A comes to be resolved immediately 

 into B, so that movement is inhibited at the start. On the other hand, the 

 physiological condition C, concomitant with a turn to the left, is regularly 

 resolved into the condition D, concomitant with reaching the water, and 

 inducing a positive reaction. This resolution becomes automatic, so 

 that the turn to the left is followed at once by forward motion to 

 the water. In these cases the actual number of physiological states 

 that could be distinguished is, of course, greater than what we have 

 set forth above. But this does not alter in any way the general 

 principle involved. 



The law of the resolution of physiological states illustrated in the 

 foregoing examples is of the highest importance for the understanding 

 of behavior. With selection from among varied movements, it forms 

 one of the corner-stones for the development of behavior. The law 

 may be expressed briefly as follows : — 



The resolution of one physiological state into another becomes easier 

 and more rapid after it has taken place a number of times. Hence the 

 behavior primarily characteristic for the second state comes to follow 

 immediately upon the first state. 



The operations of this law are, of course, seen on a vast scale in higher 

 organisms, in the phenomena which we commonly call memory, asso- 

 ciation, habit formation, and learning. In the lower organisms the mani- 

 festations of this law are comparatively little known. This is probably 

 due largely to difficulties of experimentation. Since the law has been 

 demonstrated to hold in unicellular organisms (Stentor and Vorticella), 

 there is much reason to suppose that it is general, and that it will be 

 demonstrated in one form or another for other lower organisms. There 

 seems to be no theoretical reason for supposing it to be Kmited to higher 

 animals. Very great differences exist among different organisms as to 

 the ease with which the quick resolution of one physiological state into 

 another is established. There are likewise great differences in the per- 

 manency of existing connections among the present reaction methods. 

 Hence it does not follow, as Yerkes (1902) has well pointed out, that be- 

 cause a few experiments do not demonstrate this law in a given case, 

 the law, therefore, does not hold. In his experiments with crustaceans, 



